Energy storage module with XRAM current multiplier

ABSTRACT

An electrical machine includes as part of its stator XRAM windings for multiplying current output of the machine. The XRAM windings are coupled to switching elements that are configured to produce current multiplication for output to an external load. The XRAM windings may be in slots in the stator, or may be elsewhere in the stator, operatively coupled to other windings in the stator. The stator may be operatively coupled to a rotor and hence to an inertial energy source, such as a flywheel on the same shaft as the elements of the electrical machine. Short circuiting of select windings of the machine can advantageously cause a shifting and concentration of a machine airgap flux of the machine over other windings, and increasing their magnetic storage energy.

FIELD OF THE INVENTION

The invention is the field of pulsed power systems for transferringpower.

DESCRIPTION OF THE RELATED ART

Power conversion using the XRAM circuit techniques are known in theprior art for producing a current multiplication of a generator orsource output to permit very high current supplied to mainly pulsedelectromagnetic loads. These circuits employ a multiplicity of solidstate or triggered vacuum switches which quickly reconnect internalenergy storage elements within the XRAM generator to reconfigure acircuit by placing series charged energy storage elements in parallel toeffect a current multiplication. For example, in a 10-stage XRAMgenerator if there are 10 elements which are charged in series at 10 kVinput these elements are placed in parallel to yield a 1 kV output at 10times the current rating of the individual elements. In one prior artembodiment, the energy storage elements are inductive storage coils.This system has been shown to be effective and implemented in prior artalthough heavy and of low power density. This prior art requires theenergy storage elements to be outside of the main generator or sourceand consequently require significant extra space and weight for the XRAMgenerator.

SUMMARY OF THE INVENTION

An electrical machine includes stator windings that function as an XRAMgenerator.

An electrical machine includes in its stator slots motoring windings,generating (main output) windings, and XRAM windings.

An electrical machine includes XRAM windings in a stator that areoperatively coupled to other windings in slots of the stator.

According to an aspect of the invention, a dynamo-electric machineincludes: an electromagnetic structure that includes: alternatingcurrent primary windings; and polyphase secondary windings; an array ofswitching elements; and a flywheel rotating mass; wherein the primarywindings provide a motoring torque on the flywheel rotating mass andmagnetize the dynamo-electric machine; wherein the electromagneticstructure provides power, derived from transient electromagneticinductive storage within the electromagnetic structure, to the array ofswitching elements, with the switching elements configured to producecurrent multiplication for output to an external load; and wherein theflywheel rotating mass is operatively coupled to the electromagneticstructure to provide inertial energy storage.

According to an embodiment of any paragraph(s) of this summary, themachine further includes tertiary windings operatively coupled to theprimary windings and the secondary windings.

According to an embodiment of any paragraph(s) of this summary, thesecondary windings provide output power.

According to an embodiment of any paragraph(s) of this summary, thetertiary windings provide inductive energy storage.

According to an embodiment of any paragraph(s) of this summary, inoperation the tertiary windings are configurable in a series connectionfor energy storage, and are reconfigurable in a parallel connection.

According to an embodiment of any paragraph(s) of this summary, themachine further includes tertiary windings operatively coupled to theprimary windings and the secondary windings such that short circuitingof the primary windings or the secondary windings causes a shifting andconcentration of a machine airgap flux of the machine over tertiarywindings, which induces a direct or transient current in the tertiarywindings, which is used for inductive energy storage and to effect acurrent multiplication to the external load.

According to an embodiment of any paragraph(s) of this summary, theshort circuiting of the primary windings or the secondary windingscauses a shifting or concentration of the machine airgap flux from adirect magnetic axis to a quadrature magnetic axis.

According to an embodiment of any paragraph(s) of this summary, themachine contains additional electromagnetic windings arranged to producea counter-pulse output for the purpose of commutating high powerelectronic switches that are principally used to reconfigure thetertiary winding coils contained within the machine periphery into ahigh current array and to provide a high current output to the externalload that is operatively coupled to the machine.

According to an embodiment of any paragraph(s) of this summary, thereare three or more distinct levels of airgap radially-directed magneticflux over a repeatable section of the airgap periphery, with the primarywindings and the secondary windings magnetically coupled by a firstlevel flux density, and the tertiary windings coils coupled by a secondlevel of flux density, and counter-pulse coils that are coupled by athird level of flux density.

According to an embodiment of any paragraph(s) of this summary,magnitude and phase shift of the second flux level and the third fluxlevel are enhanced by means of short-circuit coils embedded in a statormagnetic core of the machine.

According to an embodiment of any paragraph(s) of this summary,magnitude and phase shift of the second flux level and the third fluxlevel are enhanced by means of short-circuit coils embedded in a rotormagnetic core of the machine.

According to an embodiment of any paragraph(s) of this summary, themachine further includes tertiary windings operatively coupled to theprimary windings and the secondary windings such that short circuitingof the primary windings or the secondary windings causes a shifting orconcentration of core magnetic flux of the machine, and subsequentlyincreases the magnetic energy storage capacity of the tertiary windings,which is used for rapid transfer of inductive energy storage and inconjunction with a switching network effects a current multiplication topower output loads.

According to an embodiment of any paragraph(s) of this summary, themachine further includes tertiary windings operatively coupled to theprimary windings and the secondary windings such that short circuitingof the primary windings or the secondary windings causes a pulsing ofcore magnetic flux of the machine, and subsequently increases themagnetic energy storage capacity of the tertiary windings, which is usedfor rapid transfer of inductive energy storage and in conjunction with aswitching network effects a current multiplication to power outputloads.

According to an embodiment of any paragraph(s) of this summary, theflywheel rotating mass is on a same shaft as other elements of themachine.

According to another aspect of the invention, an electrical machineincludes: a stator; a rotor; and windings in the stator; wherein thestator surrounds the rotor; wherein the windings in the stator include:main windings for producing output current; and pulsed winding coilsconfigured for producing a multiplied output that is greater than theoutput current.

According to an embodiment of any paragraph(s) of this summary, themachine is a doubly-fed induction machine configured to receive powerinputs to both the rotor and the stator.

According to an embodiment of any paragraph(s) of this summary, the mainwindings and the pulsed winding coils are in alternate slots of thestator, and drive different respective magnetic circuits.

According to an embodiment of any paragraph(s) of this summary, thepulsed winding coils are radially inward of the main windings, with thepulsed winding coils closer than the main windings to an airgap betweenthe stator and the rotor.

According to an embodiment of any paragraph(s) of this summary, themachine further includes counter-pulse coils on an outer periphery of astator magnetic core of the stator.

According to an embodiment of any paragraph(s) of this summary, thecounter-pulse coils have independent magnetic circuits used primarilyfor energy storage in a magnetic field.

According to an embodiment of any paragraph(s) of this summary, thecounter-pulse coils provide commutation energy for power electronicswitches connected to the machine, where the power electronic switchesrequire reverse bias to accomplish commutation.

According to an embodiment of any paragraph(s) of this summary, the mainwindings in the stator include polyphase motoring coils and polyphasegenerating coils.

According to an embodiment of any paragraph(s) of this summary, thepulsed winding coils are polyphase coils wound and concentrated in aquadrature axis of the machine; wherein the generating coils are woundand concentrated in a direct axis of the machine; and wherein themotoring coils span both the direct axis and the quadrature axis.

According to an embodiment of any paragraph(s) of this summary,simultaneous short circuiting of the motoring coils and of rotorwindings of the rotor causes a peripheral shift in airgap magnetic fluxto the generating coils or the pulsed winding coils.

According to an embodiment of any paragraph(s) of this summary, shortcircuiting of rotor windings of the rotor and open circuiting of themotoring coils provides flux shifting to enhance voltage induction intothe generating coils or the pulsed winding coils.

According to an embodiment of any paragraph(s) of this summary, thepulsed winding coils are outside of slots of the stator that contain themain windings.

According to an embodiment of any paragraph(s) of this summary, thepulsed winding coils have an independent voltage level different fromthat of the main windings.

According to an embodiment of any paragraph(s) of this summary, themachine further includes auxiliary coils coupling the pulsed windingcoils with the main windings.

According to an embodiment of any paragraph(s) of this summary, themachine further includes magnetic pole pieces operatively coupled to thepulsed winding coils, which are separated the machine main magneticcore.

According to an embodiment of any paragraph(s) of this summary, the mainwindings include generating windings that are operatively coupled to arectifier to selectively store energy in the pulsed winding coils, toallow selective high-current output from the pulsed winding coils.

According to an embodiment of any paragraph(s) of this summary, thehigh-current output is greater than an output of the generatingwindings.

According to an embodiment of any paragraph(s) of this summary, thehigh-current output is a multiple of the output of the generatingwindings.

According to an embodiment of any paragraph(s) of this summary, themachine further includes counter-pulse coils in the stator, havingindependent magnetic circuits.

According to an embodiment of any paragraph(s) of this summary, themachine further includes a switch for shorting between motoring windingsof the stator, and a rotor winding of the rotor.

According to a further aspect, a system includes: two or more electricalmachines operatively coupled together; wherein outputs of the two ormore machines are combinable to power a common load; wherein each of themachines is configured to have a different respective shaft speed and/ora different stored energy capability; and wherein the machines arecoupled together for sequential or parallel feeds from the machines.

To the accomplishment of the foregoing and related ends, the inventioncomprises the features hereinafter fully described and particularlypointed out in the claims. The following description and the annexeddrawings set forth in detail certain illustrative embodiments of theinvention. These embodiments are indicative, however, of but a few ofthe various ways in which the principles of the invention may beemployed. Other objects, advantages and novel features of the inventionwill become apparent from the following detailed description of theinvention when considered in conjunction with the drawings.

BRIEF DESCRIPTION OF DRAWINGS

The annexed drawings, which are not necessarily to scale, show variousaspects of the invention.

FIG. 1 is a schematic diagram of a power transfer system or machine inaccordance with an embodiment of the invention.

FIG. 2 is a schematic diagram of a power transfer system or machine inaccordance with an embodiment of the invention.

FIG. 3 is a schematic diagram of a power transfer system or machine inaccordance with an embodiment of the invention.

FIG. 4 is a schematic diagram of a power transfer system or machine inaccordance with an embodiment of the invention.

FIG. 5 is a schematic diagram of a stator winding layout in accordancewith an embodiment of the invention.

FIG. 6 is a schematic diagram of a power transfer system or machine inaccordance with an embodiment of the invention.

FIG. 7 is a schematic diagram of a power transfer system or machine inaccordance with an embodiment of the invention.

FIG. 8 is a graph qualitatively illustrating changes in airgap fluxlevel during operation of a machine according to an embodiment of theinvention.

FIG. 9 is a winding diagram illustrating an example XRAM coil windingaccording to an embodiment of the invention, part of a machine thatincludes the windings shown in FIGS. 10 and 11.

FIG. 10 is a winding diagram illustrating an example motor windingaccording to the same embodiment as FIG. 9's winding.

FIG. 11 is a winding diagram illustrating an example generator windingaccording to the same embodiment as FIG. 9's winding.

FIG. 12 is a winding diagram illustrating an example rotor windingaccording to the same embodiment as FIG. 9's winding.

FIG. 13 is a cross-sectional view showing windings in a stator accordingto an embodiment of the invention.

FIG. 14 is a cross-sectional view showing windings in a stator accordingto an embodiment of the invention.

FIG. 15 is a cross-sectional view showing windings in a stator accordingto an embodiment of the invention.

FIG. 16 is a schematic diagram of a power transfer system that includesthe machine of FIG. 15.

FIG. 17 shows a schematic diagram of a pulsed load circuit that is partof the power transfer system of FIG. 16.

FIG. 18 is a flow chart illustrating steps in the operation of thesystem of FIG. 16.

FIG. 19 shows a parametric design curve for an XRAM machine, with afirst condition/configuration highlighted.

FIG. 20 shows the parametric design curve of FIG. 19, with a secondcondition/configuration highlighted.

DETAILED DESCRIPTION

An electrical machine includes as part of its stator XRAM windings formultiplying current output of the machine. The XRAM windings are coupledto switching elements that are configured to produce currentmultiplication for output to an external load. The XRAM windings may bein slots in the stator, or may be elsewhere in the stator, operativelycoupled to other windings in the stator. The stator may be operativelycoupled to a rotor and hence to an inertial energy source, such as aflywheel on the same shaft as the elements of the electrical machine.Short circuiting of select windings of the machine can advantageouslycause a shifting and concentration of a machine airgap flux of themachine over other windings, and increasing their magnetic storageenergy.

Other arrangements are possible based on the principles described belowin connection with certain embodiments. For example the arrangementsshown herein can be inverted, whereby primary, secondary, and tertiarywindings are on the rotor and excitation windings are on the stator.

Various embodiments described herein include motoring windings,generating windings, and XRAM or counter-pulse (CP) windings.Alternatively the motoring windings may be considered primary windings,the generating windings may be considered secondary windings, and theXRAM or CP windings may be considered tertiary windings.

In general, an electrical machine has a primary winding, typically onstator, that is distributed in both direct and quadrature axes. Thesecondary winding also typically on the stator is concentrated on thedirect axis. The tertiary winding also on the stator is concentrated onthe quadrature axis. During the mode when output system requires thetertiary winding to be used for either energy storage or counter-pulsegeneration, the airgap flux is shifted by several means from peaking inthe direct axis to peaking in the quadrature axis and consequently thevoltage induced in the tertiary winding advantageously escalates beyondnormal values.

One such means is to short-circuit the primary winding at its terminals(with power source removed) which shifts airgap flux from the peripheralstator segment occupied by the primary winding to the tertiary orcounter-pulse peripheral zone. Another means is to short circuit theterminals of wound polyphase rotor which has the effect of shiftingairgap flux to peak in the stator quadrature axis of the tertiarywinding. A third means is to employ short-circuiting “null flux” closedloops at various peripheral positions along the stator core which arecontrolled to create a terminal short circuit on these loops by a set ofsolid-state switches or vacuum circuit breakers. The magnetic fluxthrough a short-circuited closed loop is low or close to zero and thiscauses airgap flux to shift peripheral position to where it peaks.

FIG. 1 shows a synchronous electrical machine 10 with two sets of statorwindings for providing both a) main pulse output power, and b)integrated inductive storage coils fitted around the stator peripherywhich serve to function in the XRAM switching circuit for the currentmultiplication. The two magnetic circuits are functionally decoupled inactual operation since the main and XRAM windings are in use at separatetimes although share a common magnetic circuit. A prime mover providesmechanical input power to the electrical machine and flywheel.

The windings include main windings 12, 14, and 16, and secondarywindings 22, 24, 26, and 28. The secondary windings 22-28 are shown aspart of the electrical machine 10, and also are shown as part of thecircuit diagram at the right side of FIG. 1. In FIG. 1 the secondarywindings 22-28 are shown both in the left side of the figure as part ofthe electrical machine 10, and in the right side of the figure, whichshows a functional circuit diagram indicating the interconnectionbetween the secondary windings 22-28 in their use for energy storage andcurrent multiplication, as an XRAM circuit.

XRAM circuit techniques can be used for producing a currentmultiplication of a generator or source output to permit very highcurrent supplied to mainly pulsed electromagnetic loads. Such XRAMcircuits use multiple solid state or triggered vacuum switches thatquickly reconnect internal energy storage elements within an XRAMgenerator to reconfigure a circuit by for placing series charged energystorage elements (Ls₁-Ls₄, shown as the coils 22-28) in parallel toeffect a current multiplication. The number of stages/elements and thecorresponding amount of multiplication of current may take on any of avariety of values. For example, in a ten-stage XRAM generator if thereare 10 elements that are charged in series at 10 kV input, theseelements may be placed in parallel to yield a 1 kV output at ten timesthe current rating of the individual elements. The secondary windings22-28 themselves are configured to function as the individual elementsof an XRAM generator, and distributed around the machine periphery, e.g.at 90 degree electrical spacing.

The main windings 12-16 produce polyphase AC output at a high voltageand low current. This polyphase high-voltage low-current AC output isrectified to high-voltage low-current DC by a rectifier 30. This DCcurrent is used to charge the input stages to the four XRAM stages 42,44, 46, and 48, each one corresponding to one of the secondary windings22-28. The arrangement shown includes inductive storage coils Ls₁-Ls₄(the secondary windings 22-28) and counter-pulsed by electrostaticcapacitors C₁-C₄ (reference numbers 52, 54, 56, and 58) for the internalenergy storage elements. The four-stage XRAM is shown along with fourmain reverse conducting thyristors (RCT) 62, 64, 66, and 68, and eightpower diodes 71, 72, 73, 74, 75, 76, 77, and 78. The final output switch80 can be a thyristor or similar high current switching device such as atriggered vacuum switch. Output is provided to a load 84, which may be anon-linear load.

In one embodiment the synchronous machine 10 is a wound-field electricalgenerator. The main stator windings 12-16 are energized first by a DCexcitation winding on the rotor. The output from the main statorwindings 12-16 is used after AC/DC rectification in the rectifier 30(and capacitive storage capacitor intermediate storage 86) toinductively charge the “N” (e.g., 4) storage coils 22-28 that are inseries connection, with DC current I₁. The thyristors Th₁-Th₄ (referencenumbers 62-68) are gated to conduct forward current to charge theinductor elements 22-28 and share the source voltage equally. When theinductors 22-28 reach the steady state value of current, then a loadswitch thyristor Th_(L) (reference number 80) is closed, and all the “N”storage coils (the secondary coils 22-28) are in parallel, and outputcurrent I₁ has been multiplied by a factor of N:1.

Reference is at times made herein to a machine having N storage coils.In such references it should be appreciated that N represents anyinteger greater than 1.

This current-multiplication process also works with a permanent-magnetfield synchronous AC generator that has a nearly constant airgap flux atall times, and may be superior to a wound-DC field machine, which canhave greater variation in magnitude of airgap flux. In such analternative arrangement the AC/DC rectifier has an intermediate energystorage with an electrostatic capacitor bank. Since the voltage is highat this stage, the capacitor bank is compact and efficient. Energytransfer is from the flywheel through the electrical machine then to theDC rectifier capacitor then routed to the inductive storage coilsmounted on the machine periphery. Thus there are three distinctmechanisms of energy storage.

FIG. 2 shows a simplified arrangement of using a wound field inductionelectrical machine 110 with two sets of stator windings for providingboth main pulse output power, using the main windings 112, 114, and 116,and integrated inductive storage coils 122, 124, 126, and 128, fittedaround a stator periphery. The secondary windings (inductive storagecoils) 122-128 serve to function in the XRAM switching circuit for thecurrent multiplication. The two magnetic circuits are functionallydecoupled in actual operation since the main windings 112-116 and theXRAM windings 122-128 are in use at separate times, although both setsof windings share a common magnetic circuit.

Consider the operation of an induction machine that is a polyphasewound-AC field induction generator and is already up to speed with asignificant flywheel for energy storage. The main stator windings112-116 are energized first by an AC excitation slip-frequency rotorwinding 130 and associated power supply 184. The stator-generated outputis used after AC/DC rectification (in a rectifier 132), and aftercapacitive storage capacitor intermediate storage 134, to inductivelycharge the “N” (e.g. 4) storage coils 122-128. The coils 122-128 arecharged in series connection through thyristors Th₁-Th₄ (referencenumbers 162, 164, 166, and 168) with DC current. When the inductorsreaches the steady-state value of current, then load switch thyristorTh_(L) (reference number 180) is closed and all “N” storage coilsLs₁-Ls_(N) (the secondary coils 122-128 in the illustrated embodiment)are in parallel and output current has been multiplied by a factor ofN:1. A variable-voltage variable-frequency (WVF) power supply 184powering the rotor circuit 130 also has the ability to curtail activeexcitation and short-circuit the rotor winding(s) 130 to benefit theoverall scheme. This lowers the impedance of the secondary coils, whichis advantageous. When the storage inductors (the secondary coils122-128) are charged to full rated current and main output windingcurrent is near zero, the rotor winding(s) are short circuited at theirterminals by either the WVF drive 184 or a separate shorting switch (orvacuum breaker), and the machine airgap flux will peripherally shift andcreate a DC transient component of current in each storage coil inaddition to the first DC current. Energy transfer is from the flywheelthrough the electrical machine then to the DC rectifier capacitor (forshort time period) then routed to the inductive storage coils 122-128mounted on the machine periphery.

FIG. 3 shows an embodiment in which a synchronous electrical machine 210has two sets of stator windings that include main windings 212, 214, and216, for providing main pulse output power, and integrated inductivestorage coils (secondary windings) 222, 224, 226, and 228, fitted aroundthe periphery of a stator of the machine 210. The secondary windings222-228 serve to function in the XRAM switching circuit for the currentmultiplication. There are also external polyphase line-to-lineshort-circuit switches S1 and S2 (reference numbers 236 and 238) on thestator main winding terminals. When the switches S1 and S2 (referencenumbers 236 and 238) are closed, this reduces the impedance of thepulsed secondary windings 222-228. The two magnetic circuits on thestator are functionally decoupled in actual operation since the main andXRAM windings are in use at separate times although share a commonmagnetic circuit.

The synchronous machine may be a permanent magnet (PM) field electricalgenerator or may be a DC-excited field machine with a wound rotor. Themain stator windings 212-216 are excited at constant rotor flux by thePM system. Output is used after AC/DC rectification (in a rectifier232), and after capacitive storage capacitor intermediate storage 230,to inductively charge the “N” (e.g. 4) storage coils 222-228. The coils222-228 are charged in series connection with DC current. When theinductors Ls₁-Ls₄ (the secondary coils 222-228) reach the steady statevalue of current, the switches 236 and 238 are closed, shorting the mainstator output and causing the rotor flux to shift spatially in theairgap by about 90 electrical degrees within a few milliseconds.Although the rotor flux remains about constant, it is now concentratedamongst the inductive storage coils 222-228. The effective magneticpermeance and effective impedance of the main stator winding decreasesrapidly when the stator short circuit occurs, the magnetic steel is nowin a saturation region and the overall terminal impedance of the mainstator coils becomes lower. This shifting of radial airgap flux resultsin a transient component of direct current being induced into thestorage coils and enhancing the overall current output multiplicationbeyond a simple N stage multiplication. The load switch thyristor Th_(L)(reference number 280) is closed and all “N” storage coils (thesecondary coils 222-228 in the illustrated embodiment) are reconfiguredin parallel and output current has been multiplied by a factor ofgreater than N:1.

A diode D₁₃ (reference number 242) protects the rectifier 232 fromreverse voltage transients, and ensures that when an air-blast breaker240 opens, that the current I₁ is maintained. A flywheel 250 isoperatively coupled to the machine 210.

FIG. 4 shows a further embodiment, a machine 410 that uses inductivestorage for the XRAM generator, and also advantageously uses a set ofwound polyphase stator coils placed within the doubly-fed inductionelectrical machine (DFIM) 410 to store XRAM energy. This arrangementavoids having to use external discrete coils for the XRAM. The machine410 has a rotor 412 and a stator 414. The rotor 412 has a rotor windingR1 (reference number 422). The stator 414 has a main stator winding S2(reference number 424), and a series of auxiliary windings S3, S4, S5,and S6 (reference numbers 432, 434, 436, and 438).

FIG. 4 shows three reverse conducting thyristor (RCT) switching devices442, 444, and 446 external to the machine 410, and eight power diodesD1-D8 (reference numbers 451, 452, 453, 454, 455, 456, 457, and 458) toplace the machine coils 432-438 in parallel for creation of a highcurrent pulsed output. The main output thyristor is a unidirectionalswitching device T₁ (reference number 480). The DFIM 410 has the woundpolyphase rotor (winding R₁, reference number 422) that is excited by avariable-voltage variable-frequency power supply (WVF inverter) 464,which is fed from either a DC or AC auxiliary power source 466. Therotor excitation also contains a polyphase shorting switch 468 thatcompletely short circuits the rotor circuit 412 at its terminals, so asto enable the XRAM mode. The main power is supplied to the DFIM throughthe stator motoring winding S1 (reference number 470) from a machine,such as a turbo-generator 472. The DFIM 410 is mechanically connected toa flywheel energy storage device 420 that contains kinetic energy E1.Shaft speed/energy decrement/increment of DFIM is part of the normaloperation.

The main DFIM output winding 424 is designated S2 in the illustration,and as shown in drawing is a single-phase stator winding as part of anoverall polyphase system. The special XRAM coils on the DFIM stator (forone phase) are designated as same-phase S3, S4, S5 and S6 coils(reference numbers 432, 434, 436, and 438) and are directly connected toswitching circuitry (reference numbers 442-446), and to a full wavebridge (FWB) main rectifier 494, which supplies the DC charging currentI2. The coils S3, S4, S5 and S6 (432-438) are wound on the same machinestator magnetic circuit as the main motoring/generating coils (424), andutilize the machine main airgap flux yet only during a short period oftime. In normal generating operation, the rotor is excited by the WVFsupply 464, and initiates the main airgap flux of the machine 410. Thereverse conducting thyristors (RCT) 442-446 connects these four coils432-438 in series prior to the short circuit mode.

For pulsed power operation, once the main output DC current is rectifiedand current is circulated into coils S2-S6, the rotor is short circuitedwhich shifts the majority of airgap flux into the coils S2-S6 whichboosts this current. Furthermore, upon a rotor short circuit theinductive reactance of coils S2-S6 significantly decreases to what isknown as a “bore reactance” which permits high currents to flow withlower reactance. The counter-pulse current I5-I8 provided byelectrostatic capacitors C1-C4 (reference numbers 471, 472, 473, and474) turns OFF the RCT switches 442-446 and the circuit is reconfiguredso that Coils S2-S6 are now in parallel to feed the common load. Mainoutput switch 480 combines component currents in the diodes 451-454 intoa common load 482. The electrostatic capacitors C1-C4 are smaller energystorage devices and the majority of energy storage is from the coilsS2-S6 within the electrical machine. The system is compact andadvantageously represents a significant reduction in weight and size incomparison with prior approaches.

FIG. 5 shows a system 500 which includes a pair of low-current DFIMs 502and 504, which may be similar to the doubly-fed machine described abovein FIG. 4. Input power 510 may be provided to respective frequencyconverters 512 and 514, and to respective rotor VVVF excitationconverters 516 and 518. The main frequency converters 512 and 514provide power to respective stator inputs 522 and 524, and theconverters 516 and 518 provide excitation power to respective rotors 526and 528. Flywheel energy storage systems 532 and 534 are also coupled tothe respective rotors 526 and 528. Stator output main coils 542 and 544are coupled to respective full-wave-bridge controlled rectifiers 546 and548. Secondary output coils 552 and 554 are coupled to respectiveXRAM-thyristor switch networks 556 and 558. Output then goes throughrespective final pulse shaping networks (PSNs) or pulse forming networks(PFNs) in blocks 562 and 564, then on through respective outputthyristor switch arrays 566 and 568, and then out to a pulsed load 570.

FIG. 6 shows another embodiment, an electrical machine 610 with afour-stage XRAM showing the arrangement of three phases around thestator periphery of the electrical machine 610, for example with either84 or 168 total stator slots. The machine 610 is a DFIM machine withfour poles. Main output windings are in tops of stator slots: 72 slotsas 3-phases, 6 slots per pole per phase arranged as 3 separate groupsdouble-layer lap winding each having 2 slots/pole. Main motoringwindings are in bottom of stator slots: 84 coils for a 3-phase system,21 coils per phase, 7 coils per pole per phase, as a lap wounddouble-layer winding. For the XRAM coils there are a total of 12 coilsin a 3-phase system spaced equally around stator periphery embedded instator slots closest to airgap. In the machine 610 the rotor winding is4 pole wound as “skip pole” delta connected winding in typically 36 or72 slots.

FIG. 7 shows an embodiment of a machine 710 where the XRAM (N=4)external storage inductors are eliminated by having the electricalmachine provide the magnetic flux to link these inductors to main airgapflux and create a magneto-inductive storage for XRAM coils S3, S4, S5and S6 (collectively reference number 720). Diodes in some priorarrangements are also eliminated, leaving only four full-wave-bridgepower diode assemblies for a four-stage XRAM, shown as an XRAM diodearray 730. RCT switching devices are used when very high currents suchas 10,000 Amps are involved; otherwise a lower current solid-stateswitching device such as an IGBT or MOSFET which can commutate its owncurrent by gate turn-off command can be effectively used. In FIG. 7, thecoils S2-S6 (a stator main AC output 712 and the XRAM coils 720) arewound on the electrical machine stator core 714 and respond to a suddenshort circuit of the rotor circuit R1 (reference number 716) on a rotor718. An AC or DC excitation source 740 and a VVVF excitation inverter742 provide power to the rotor circuit R1 (reference number 716). Afterthe excitation source 740 is shut off and when system ready for a highcurrent discharge, the rotor circuit R1 (reference number 716) is shortcircuited through a line-to-line electronic switch (such as ananti-parallel thyristor combination) 746, which peripherally shiftsairgap flux into the stator generating coil 712, or the XRAM coils 720.This consequent shifting of the airgap radial magnetic flux is notnulled but rather accumulates in the XRAM dedicated coils or sector andso reduces their inductive reactance, which is advantageous for creatinghigh output current. In certain machine winding layouts, it is alsobeneficial to short-circuit the stator motoring winding 770 aftermachine 710 is up to speed as shown with the two 3-phase vacuum breakersVB and the shorting inductor Lx (collectively reference number 746)connected as line to line. Simultaneously the rotor winding R1 (716) andstator winding S1 (712) short circuiting mode results in a high voltageinduction into the S2-S6 coils (XRAM coils 722-728) which is used toreverse bias the set of RCT thyristors 750. The coils S2-S6 are placedclosest to the machine airgap to react most effectively with theshifting of stator airgap flux.

In the embodiment shown in FIG. 7 the counter-pulse capacitors in theembodiment of FIG. 4 (for example) are eliminated by having theelectrical machine auxiliary output winding 760 provide thecounter-pulse current to effect a commutation of the three RCT thyristorswitches 750. The machine counter-pulse circuits CP 760 are connecteddirectly across each RCT. RCT switching devices may be used when veryhigh currents such as 10,000 Amps are involved. Otherwise a lowercurrent solid-state switching device such as an IGBT or MOSFET, whichcan commutate its own current by gate turn-off command, can beeffectively used. In FIG. 7, the coils S3-S6 (stator XRAM coils 720) andcounter pulse coils 760 are wound on the common electrical machinestator core and respond (by having high induced voltage) to a suddenshort circuit of the rotor circuit. The rotor circuit R1, afterexcitation inverter VVVF is shut off and when system is ready for a highcurrent discharge, is then short-circuited through a line to lineelectronic switch (or vacuum breakers) 746 which peripherally shiftsairgap flux into the stator generating, CP and XRAM coils.

The machine 710 is linked to a pulsed DC load 764 through diode array730. Other similar machines, represented in FIG. 7 by XRAM diode arrays772 and 774, also may be coupled (such as in parallel) to provide powerto the load 764.

The special electrical induction machine has an internal space transienteffect which produces a non-symmetrical distribution of flux around theairgap periphery in contrast to normal operation where airgap flux issymmetrically distributed. This non-symmetrical distribution of flux isadvantageous.

FIG. 8 shows a spatial distribution of airgap flux when a segment of themachine stator periphery is occupied by a combination of a motoring orgenerating winding and a specific peripheral sector devoted to both XRAMcoil and counter-pulse coils in a 72 or 144 slot stator of 4 or 8 polesrespectively. The normal flux density for the motoring winding B₀ may be0.70 Tesla, the XRAM flux density B₁ may be 0.85 Tesla and thecounter-pulse airgap flux density B₂ at 0.95 Tesla. These two higherflux densities are a function of short circuiting the motoring windingat its terminals which cause a shifting of the airgap magnetic flux outof the motoring zone and into the XRAM zones. This is a form of fluxcompression. That is the flux that would normally encircle 54 slots issqueezed into a zone of 18 slots causing an inherent 4:1 fluxcompression if the short circuit were perfect. Since there is a leakageinductance in the motoring winding and the short circuit current islimited by the stator to rotor leakage reactance and the end-windingleakage, the inherent flux compression might be a 2:1 ratio which isacceptable. Here it is sent the XRAM and CP coil sector occupies 18slots out of 72 slots, or 25% of the machine periphery. In an alternateembodiment, the XRAM and CP coils occupy 9 slots out of 72 slots, or12.5% of the machine periphery which is more efficient.

FIGS. 9-12 shows an example electrical machine coil system. FIGS. 9-11show sample layouts of a 4-pole 3-phase machine in 84 stator slotsshowing coil groups for (respectively) XRAM winding (layout 802 in FIG.9), motoring winding (layout 804 in FIG. 10), and generator winding(layout 806 in FIG. 11) on a common frame. The XRAM winding has 48coils, the motoring winding has 84 coils and the generating winding has36 coils. Thus each stator winding can have unique voltage levels andunique power input/output levels. FIG. 12 shows preferred rotor windinglayout 808 for a 4-pole DFIM machine in 36 rotor slots to match thestator top drawing. The winding layout can be extended to other polenumbers such as 6, 8 and 10 poles with stator slot numbers starting at72. The rotor can be excited by a slip-ring assembly or by a brushlessexciter, as is well known in the art.

FIGS. 13-15 shows three different cross sections of stator slots showingthree types of configurations for implementing XRAM windings on thestator frame. The arrangements shown in FIGS. 13-15 may be used as partor in connection with other aspects of the various other embodimentsshown therein.

FIG. 13 shows an approach of combining an XRAM winding into same slot asthe generating and motoring windings shown as 2 slots/pole/phase, in amachine 810 having a stator 812. The stator 812 surrounds a rotor 814,and the stator 812 has slots 816 and 818 for receiving the variouswindings. Only the two slots 816 and 818 are shown in FIG. 13 but itwill be appreciated that the stator 812 may have slots evenlycircumferentially spaced around the stator 812. The stator 812 and therotor 814 define an airgap 820 between them, with the airgap 820radially inward of the stator 812 and radially outward of the rotor 814.An XRAM winding 824 is located in the slots 816 and 818 closest to theairgap 820 to minimize magnetic permeance and minimize magneticreactance. A motoring winding 828 deepest in the slots 816 and 818,yielding a highest magnetic permeance/reactance of the group. A mainoutput winding 834 is in the slots 816 and 818, radially between theXRAM winding 824 and the motoring winding 828. All the windings 824,828, and 834 are shown in FIG. 13 with internal liquid cooling conductorchannels. However it will be appreciated that other sorts of conductorcooling may be used instead.

FIG. 14 shows a cross section of a stator 862 of a machine 860. Thestator 862 surrounds a rotor 864, with an airgap 870 between the rotor864 and the stator 862. Various windings of the machine 860 are locatedin slots 872, 874, 876, and 878 of the stator 862. The windings includeXRAM windings 882 that are located in the deepest part of the statorslots 872 and 874. The windings 882 are only located in select slots(e.g., the slots 872 and 874) that are shared with a generating winding884, and not with a motoring winding 886. The motoring winding 886 isconfined to slots, such as the slots 876 and 878, where the XRAMwindings 882 are not located. Most of the machine stator periphery 860is wound with a combination of generating and motoring windings in acommon stator slot, and only a small portion of the machine's stator hasthe combined XRAM and generating windings in common slots. Thearrangement for the generating and motor windings can be standard 2-6slots/pole/phase layout whereas the XRAM winding will generally have alower number of occupied slots resulting in 1-2 slots/pole/phase. In theconfiguration shown in FIG. 14 the method of shorting at the terminalsof either the motoring or generating winding (or both) will result in aperipheral shifting of the magnetic flux in the stator core andconcentrate this flux around the XRAM windings 882, inducing anelectro-magnetic field (EMF) that will result in high voltage generationin the XRAM coils 882.

Here using a larger number of turns (e.g. 6 per slot) for the XRAMwinding results in a higher voltage induced in the XRAM winding thanwould be the applied voltage to the motoring winding or the output ofthe generating winding during a short circuit condition. In addition thelarger number of turns for the XRAM winding results in a higher terminalinductance than the generating winding; this inductance L is necessaryas an energy storage device since stored energy E=0.5*L*I². The currentI that is induced is proportional to the short circuit current of thecombined motoring and generating winding when this mode of operationoccurs.

FIG. 15 shows an embodiment of a machine 910 with a stator 912surrounding a rotor 914 with an airgap 920 there between. In the machine910 XRAM coils 936 are positioned outside of the standard machine slots934. The XRAM coils 936 have dedicated locations and dedicated magneticpole pieces 938 positioned along the outer part of the magnetic core ofthe stator 912. The magnetic pole pieces 938 are used to confine XRAMmagnetics to a specific flux path and increase energy storage of a coil.Special null flux shorting coils 940 are located in select stator slots936 and enclose the magnetic core back-iron flux to control flux densityin the radial dimension shown in FIG. 15 as D_(x). Magnetic flux linesφ1, φ2, φ3 enclose the XRAM coils 936 and develop both voltage andinductance of the XRAM coils 936. In normal operation, prior to a pulseduty, the fluxes φ1, φ2, φ3 are at a nominal value. When a pulse duty isbeing commanded, the array of shorting coils 940 are shorted through anelectronic switch (e.g., a thyristor or IGBT) and the magnetic flux φ1,φ2, φ3 rapidly increases, and the XRAM output current correspondinglyrapidly increases and is able to store energy. In an embodiment each ofthe shorting coils has its own shorting electronic switch rather thanhaving multiple shorting coils in series connection.

The machine 910 may be a DFIM, as is discussed below in connection ofthe system shown in FIG. 16. Alternatively the machine 910 may beanother type of rotating electrical machine, including synchronous orreluctance types.

FIG. 16 shows a system 950 that includes the machine 910 of FIG. 15.FIG. 16 shows an apparatus 1046 to short-circuit the null flux loopsshown in FIG. 15, which causes flux circulating around the XRAM coils todecrease. The machine 910 shown in FIG. 16 is a DFIM. The XRAM currentmultiplier scheme includes the XRAM coils 936, and the null flux coils940 around the stator core 912, as described above. The machine 910 alsoincludes short circuiting switches 960 on three null-flux loop windingsto concentrate machine flux in XRAM storage coils 936 and result in highcurrent output. Reactors X1 and X2 (reference numbers 962 and 964) areused to limit short-circuit current to safe values. Generating winding1036 is rectified and filtered at DC link 1034, then fed into XRAMswitching array 968. The XRAM electronic switching array 968 is used tocreate a high current output pulse, in a manner similar to thatdescribed above with regard to the embodiments shown in FIGS. 3 and 4.The switching array 968 provides current I_(L) to a pulsed load 972,through a switching circuit described further below. There are fourtypes of energy storage as indicated: an electro-kinetic-flywheel E1(reference number 982), an electrochemical excitation energy source E2(reference number 984), electrostatic energy sources E2′ and E3(reference numbers 986 and 988) and an electromagnetic-XRAM source E4(reference number 990).

FIG. 17 shows a specialized load circuit 974 for the pulsed load 972,coupled to the XRAM switching array 968 (FIG. 16). The circuit 974consists of an inductor-capacitor 4-stage pulse forming network. TheXRAM switching array 968 provides current multiplication and the PFNload circuit 974 can provide a lower output impedance and a faster risetime e.g. 20 nS than the XRAM into the final load 972, which is shown asresistive element R_(L). It is a preferred embodiment to have an XRAMhigh current circuit feed a pulse forming network, such as the circuitor PFN 974, since effective pulse shaping often can require twodifferent types of circuits working in conjunction. A trigger gate pulse976 shown is provided to any number of high current switching devicessuch as ignitrons, thyristors, thyratrons, or IGBTs.

FIG. 18 shows the sequence of operation of the system 950 (FIG. 16) withits five vacuum breakers or similar electronic switches (such asbilateral thyristor pairs), three switches or circuit breakers of whichare used for creating short circuiting conditions to shift electricalmachine flux within the machine stator core causing buildup of magneticflux surrounding the XRAM coils and thereby produce an increase in coilinductive stored energy. The method 1000 begins in step 1002, with whenvacuum breakers VB₁ and VB₃ (reference numbers 1022 and 1024 in FIG. 16)are closed, and VVVF-1 and VVVVF-2 inverter drives (reference numbers1026 and 1028 in FIG. 16) are started.

In step 1003 a rotor winding R1 (reference number 1032 in FIG. 16) isexcited to drive the DFIM 910 (FIG. 16) to a maximum speed and a maximumkinetic energy. Then, in step 1004, there is a transfer of kineticenergy to the electrostatic energy source E3 (reference number 988 inFIG. 16), charging a capacitor C1 (reference number 1034 in FIG. 16)through a generating winding S2 (reference number 1036 in FIG. 16).

In step 1006 the system 950 (FIG. 16) enters into a flywheel coast mode,with the breaker VB₁ (1022) opened, and the VVVF-1 motoring drive 1026shut off. In step 1007 the XRAM inductors (parts of the XRAM switchingarray 968 (FIG. 16)) are charged, through the XRAM windings S3 (the XRAMcoils 936 of FIG. 16) and from a low current originating from theelectrostatic energy source E3 (reference number 988 in FIG. 16).

In step 1008 the rotor circuit vacuum breaker VB₃ (reference number 1024in FIG. 16) is opened, and the rotor excitation is turned off at theVVVF-2 motoring drive 1028, hereby waiting for all of the electrostaticcharge to be transferred from the electrostatic energy source E3(reference number 988 in FIG. 16) to the XRAM switching array E4(reference number 990 of FIG. 16). Following that, in step 1009,shorting vacuum breakers VB₂ and VB₄ (reference numbers 1042 and 1044 inFIG. 16) are closed, to start flux shift along the stator slots 936(FIG. 15). In step 1011 vacuum breakers VB₅ (reference number 1046 inFIG. 16) are closed, shorting the null flux coils 940 (FIG. 15) to shiftstator magnetic core flux.

Then in step 1012 the XRAM output electronic switches 960 are closed, toreconfigure the XRAM coils 936 (FIG. 16) in parallel. Finally in step1014 there is a transfer of the high current (multiplied I_(L) current)to the pulsed load 972 (FIG. 16). The high current I_(L) is multipliedby the number n of XRAM coils over the current produced by a single coilI₁: I_(L)=n·I₁. This cycle may be repeated as necessary to provide acontinuous stream of high-current pulses as required.

FIGS. 19 and 20 show a parametric design curve for an XRAM machinespecific to an induction machine with shorted stator primary coils andnon-shorted secondary or tertiary coils. The vertical axis is thenormalized product of in-phase flux density times synchronous speed,divided by the product of rotor resistivity times stator currentloading. The design parameter G is the ratio of magnetizing reactanceX_(m) to rotor resistance R_(r) and shown for specific case of G=30,which is representative of a large induction machine. The rotor can be acage rotor or a wound polyphase rotor. FIGS. 19 and 20 show the airgapradially-directed flux density B_(p) as a function of airgap peripheraldistance for the case when the stator motoring winding (preceding statorpole location zero) is short circuited on all phases, the flux densitypeak location shifts and the flux density builds up from zero in anoscillatory fashion for the subsequent windings (either secondary ortertiary coils) spaced along the stator. The normal flux density is 5.0per unit (shown as a straight horizontal line) unit under the conditionstator motoring coils are not short circuited and this is a constantairgap flux density over entire periphery. The direct and quadratureaxes of the machine are not stationary but rather move in spatiallocation as a function of slip value. The real electrical torque inNewtons of the generating windings which feeds energy or power to theXRAM coils is the integral of the airgap flux density B_(p) (in Tesla)times the stator current loading J_(s) (A/meter periphery). The productof torque times shaft speed in radians/second gives the electrical powergenerated in Watts. The flux density spatial shifting occurssimultaneously with stator short circuiting.

FIG. 19 specifically highlights a case when electromagnetic slip of thegenerating winding is held to 20% (0.20 per unit); at point P₁ the fluxdensity is 8.37 per unit at pole 4 (termed a Direct Axis) and when thecoils are at point P₂ the flux density is 2.40 per unit at pole 8(termed a Quadrature Axis). The difference in flux due to flux shiftingis large e.g. using the above numbers a ratio of 3.48:1. Generatingcoils can be distributed and arranged to be between positions P₁ and P₂along the red curve. However it is advantageous to place tertiary orcounter-pulse coils at Pole 4 or position P₁ to maximize the effects offlux shifting and maximize voltage induction.

FIG. 20 specifically highlights a case when slip of the generatingwinding is held to 5% (0.05 per unit). At point P₃ the flux density islow at 2.64 per unit at pole 4 (a new Quadrature Axis) and when thecoils are at point P₄ the flux density is higher at 8.25 per unit atpole 8 (now a new Direct Axis). The difference in flux due to fluxshifting is now reversed and large e.g. using the above numbers a ratioof 1:3.12. Secondary coils can be distributed and arranged to be betweenpositions P₃ and P₄ along the red curve. However it is advantageous toplace tertiary or counter-pulse coils at position P₄, i.e. at Pole 8, tomaximize the effects of flux shifting and maximized voltage induction.Thus it is clear that if the electromagnetic slip value of thisinduction machine can be controlled by either phasing of the rotorcurrents or by the net torque loading by the machine, the locations ofpeak and minimum airgap flux density are continuously repeatable andcontrollable by design.

Although the invention has been shown and described with respect to acertain preferred embodiment or embodiments, it is obvious thatequivalent alterations and modifications will occur to others skilled inthe art upon the reading and understanding of this specification and theannexed drawings. In particular regard to the various functionsperformed by the above described elements (components, assemblies,devices, compositions, etc.), the terms (including a reference to a“means”) used to describe such elements are intended to correspond,unless otherwise indicated, to any element which performs the specifiedfunction of the described element (i.e., that is functionallyequivalent), even though not structurally equivalent to the disclosedstructure which performs the function in the herein illustratedexemplary embodiment or embodiments of the invention. In addition, whilea particular feature of the invention may have been described above withrespect to only one or more of several illustrated embodiments, suchfeature may be combined with one or more other features of the otherembodiments, as may be desired and advantageous for any given orparticular application.

What is claimed is:
 1. A dynamo-electric machine comprising: anelectromagnetic structure that includes: alternating current primarywindings; and polyphase secondary windings; an array of switchingelements; and a flywheel rotating mass; wherein the primary windingsprovide a motoring torque on the flywheel rotating mass and magnetizethe dynamo-electric machine; wherein the electromagnetic structureprovides power, derived from transient electromagnetic inductive storagewithin the electromagnetic structure, to the array of switchingelements, with the switching elements configured to produce currentmultiplication for output to an external load; and wherein the flywheelrotating mass is operatively coupled to the electromagnetic structure toprovide inertial energy storage.
 2. The machine of claim 1, furthercomprising tertiary windings operatively coupled to the primary windingsand the secondary windings; wherein the secondary windings provideoutput power; wherein the tertiary windings provide inductive energystorage; and wherein in operation the tertiary windings are configurablein a series connection for energy storage, and are reconfigurable in aparallel connection.
 3. The machine of claim 2, further comprisingtertiary windings operatively coupled to the primary windings and thesecondary windings such that short circuiting of the primary windings orthe secondary windings causes a shifting and concentration of a machineairgap flux of the machine over tertiary windings, which induces adirect or transient current in the tertiary windings, which is used forinductive energy storage and to effect a current multiplication to theexternal load.
 4. The machine of claim 3, wherein the short circuitingof the primary windings or the secondary windings causes a shifting orconcentration of the machine airgap flux from a direct magnetic axis toa quadrature magnetic axis.
 5. The machine of claim 3, wherein themachine contains additional electromagnetic windings arranged to producea counter-pulse output for the purpose of commutating high powerelectronic switches that are principally used to reconfigure thetertiary winding coils contained within the machine periphery into ahigh current array and to provide a high current output to the externalload that is operatively coupled to the machine.
 6. The machine of claim3, wherein there are three or more distinct levels of airgapradially-directed magnetic flux over a repeatable section of the airgapperiphery, with the primary windings and the secondary windingsmagnetically coupled by a first level airgap flux density, and thetertiary windings coils coupled by a second level of airgap fluxdensity, and counter-pulse coils that are coupled by a third level ofairgap flux density; and wherein magnitude and phase shift of the secondflux level and the third flux level are enhanced by means of switchableshort-circuit coils embedded in a stator magnetic core of the machine.7. The machine of claim 3, wherein there are three or more distinctlevels of airgap radially-directed magnetic flux over a repeatablesection of the airgap periphery, with the primary windings and thesecondary windings magnetically coupled by a first level flux density,and the tertiary windings coils coupled by a second level of fluxdensity, and counter-pulse coils that are coupled by a third level offlux density; and wherein magnitude and phase shift of the second fluxlevel and the third flux level are enhanced by means of switchableshort-circuit coils embedded in a rotor magnetic core of the machine. 8.The machine of claim 1, further comprising tertiary windings operativelycoupled to the primary windings and the secondary windings such thatshort circuiting of the primary windings or the secondary windingscauses a spatial shifting or concentration of core magnetic flux of themachine, and subsequently increases the magnetic energy storage capacityof the tertiary windings, which is used for rapid transfer of inductiveenergy storage and in conjunction with a switching network effects acurrent multiplication to power output loads.
 9. The machine of claim 1,further comprising tertiary windings operatively coupled to the primarywindings and the secondary windings such that short circuiting of theprimary windings or the secondary windings causes a pulsing of coremagnetic flux of the machine, and subsequently increases the magneticenergy storage capacity of the tertiary windings, which is used forrapid transfer of inductive energy storage and in conjunction with aswitching network effects a current multiplication to power outputloads.
 10. The machine of claim 1, wherein the flywheel rotating mass ison a same shaft as other elements of the machine and is configured toaccept or yield bidirectional flow to other components of the machine.11. An electrical machine comprising: a stator; a rotor; and windings inthe stator; wherein the stator surrounds the rotor; wherein the windingsin the stator include: main windings for producing output current; andpulsed winding coils configured for producing a multiplied output thatis greater than the output current.
 12. The machine of claim 11, whereinthe machine is a doubly-fed induction machine configured to receivevoltage inputs to both the rotor and the stator.
 13. The machine ofclaim 11, wherein the main windings and the pulsed winding coils are inalternate slots of the stator, and drive different respective magneticcircuits.
 14. The machine of claim 13, wherein the pulsed winding coilsare radially inward of the main windings, with the pulsed winding coilscloser than the main windings to an airgap between the stator and therotor.
 15. The machine of claim 11, further comprising: counter-pulsecoils on an outer periphery of a stator magnetic core of the stator;wherein the counter-pulse coils have independent magnetic circuits usedprimarily for energy storage in a magnetic field.
 16. The machine ofclaim 15, wherein the counter-pulse coils provide commutation energy forpower electronic switches of the machine, where the power electronicswitches require reverse bias to accomplish current commutation.
 17. Themachine of claim 11, wherein the main windings in the stator includemotoring coils and generating coils; wherein the pulsed winding coilsare polyphase coils wound and concentrated in a quadrature axis of themachine; wherein the generating coils are wound and concentrated in adirect axis of the machine; and wherein the motoring coils span both thedirect axis and the quadrature axis.
 18. The machine of claim 11,wherein the main windings in the stator include motoring coils andgenerating coils; and wherein simultaneous short circuiting of themotoring coils and of rotor windings of the rotor causes a peripheralshift in airgap magnetic flux to the generating coils or the pulsedwinding coils, and causes an increase in flux density and stored energyover the generating coils or the pulsed winding coils.
 19. The machineof claim 11, wherein the main windings in the stator include motoringcoils and generating coils; and wherein short circuiting of rotorwindings of the rotor and open circuiting of the motoring coils providesflux shifting to enhance voltage induction into the generating coils orthe pulsed winding coils.
 20. The machine of claim 11, wherein thepulsed winding coils are outside of slots of the stator that contain themain windings; and wherein the pulsed winding coils have an independentflux and voltage level different from that of the main windings.
 21. Themachine of claim 20, further comprising: auxiliary coils coupling thepulsed winding coils with the main windings; and magnetic pole piecesoperatively coupled to the pulsed winding coils.
 22. The machine ofclaim 11, wherein the main windings include generating windings that areoperatively coupled to a rectifier to selectively store energy in thepulsed winding coils, to allow selective high-current output from thepulsed winding coils.
 23. A system comprising: two or more electricalmachines operatively coupled together; wherein outputs of the two ormore machines are combinable to power a common load; wherein each of themachines is configured to have a different respective shaft speed and/ora different stored energy capability; and wherein the machines arecoupled together for sequential or parallel feeds from the machines.